The Fourth of July is upon us, so it’s time once again to sing what is arguably our most baffling national ditty, “Yankee Doodle Dandy.” Maybe you’ve noticed: Some of the lyrics seem like the work of a prankster on acid. Who else could have conceived a vignette as bizarre as a man riding a pony into town, then sticking a feather in his cap that, for unknown reasons, he insists on calling “macaroni”?